1. Field of the Invention
This invention generally relates to a speed responsive centrifugal clutch which operates depending on the centrifugal force which in turn varies in accordance with the speed. More specifically, the present invention relates to a speed responsive one-way centrifugal clutch suitable for use as a lock-up clutch of a torque converter for transmission of rotation only in a specified direction.
2. Description of the Prior Art
In a torque converter, it is well known to use a lock-up clutch for mechanically coupling an input shaft of the driver side to an output shaft of the driven side through contact friction as the rotational speed increases to increase the centrifugal force. For example, as described in the Japanese Patent Laid-open Pub. No. 54-142459, such a lock-up clutch typically includes a shoe assembly which is moved radially outwardly to be finally brought into frictional contact with a surface of the driven side as the centrifugal force increases. In order to make the transmission of the driving force from the driving side to the driven side through the shoe assembly, it has been proposed to provide a damper; however, the provision of such a damper would tend to make the clutch as a whole larger in size. In order to cope with such a situation, there has been proposed to arrange a shoe assembly and a damper on the same circumference as disclosed in the Japanese Patent Laid-open Pub. No. 59-149617 which has been assigned to the assignee of this application and whose corresponding U.S. patent application has already issued as U.S. Pat. No. 4,690,257 which is hereby incorporated by reference.
On the other hand, such a speed responsive centrifugal clutch is often used in combination with a one-way clutch. However, in accordance with the prior art, a speed responsive centrifugal clutch and a one-way clutch are simply arranged side-by-side along a shaft, which tends to make the entire structure larger in size and difficult to manufacture and operate. Moreover, the increased space is required for installing such a combined structure. Particularly, in the case where such a combined structure is to be used in a torque converter, since the size of the clutch is already large, the size of the one-way clutch becomes relatively larger so that difficulty in designing will be encountered in making the width of the combined structure smaller.